Method and system for determining whether a portable key device is located in an active area in relation to a barrier

Abstract

It is presented a method for determining whether a portable key device is located in an active area in relation to a barrier. The method is performed in an access control device and comprising the steps of: detecting a first angle of arrival of a wireless signal from the portable key device using a first pair of separated antennas; detecting a second angle of arrival of a wireless signal from the portable key device using a second pair of separated antennas; determining a first pair of directions based on the first angle of arrival; determining a second pair of directions based on the second angle of arrival; determining a position of the portable key device to be where one of the first pair of directions intersects one of the second pair of directions; and determining whether the portable key device is located in the active area based on the position.

What is claimed is: 
     
       1. A method for determining whether a portable key device is located in an active area in relation to a barrier, wherein the active area is on the outside of the barrier, the method being performed in an access control device and comprising the steps of:
 detecting a first angle of arrival of a wireless signal from the portable key device using a first pair of separated antennas; 
 detecting a second angle of arrival of the wireless signal from the portable key device using a second pair of separated antennas, wherein the first pair of antennas is located on the outside of the barrier and the second pair of antennas is located on the inside of the barrier; 
 determining a first pair of directions based on the first angle of arrival; 
 determining a second pair of directions based on the second angle of arrival; 
 determining a position of the portable key device to be where one of the first pair of directions intersects one of the second pair of directions, wherein any intersection located between a first line between the first pair of antennas and a second line between the second pair of antennas is discarded for determining the position; and 
 determining whether the portable key device is located in the active area based on the position. 
 
     
     
       2. The method according to  claim 1 , wherein the step of detecting the first angle of arrival comprises detecting the first angle of arrival based on a time difference of receiving the wireless signal in the first pair of separated antennas and wherein the step of detecting the second angle of arrival comprises detecting the second angle of arrival based on a time difference of receiving the wireless signal in the second pair of separated antennas. 
     
     
       3. The method according to  claim 1 , wherein the first pair of separated antennas and the second pair of separated antennas contain one and only one common antenna. 
     
     
       4. The method according to  claim 1 , wherein the first pair of separated antennas and the second pair of separated antennas contain different antennas. 
     
     
       5. The method according to  claim 1 , wherein the step of determining the first pair of directions comprises determining each direction of the pair of directions as a direction from a first midpoint between the first pair of antennas with the first angle of arrival being on either side, respectively, of the first line between the first pair of antennas, and the step of determining the second pair of directions comprises determining each direction as a direction of the second pair of directions from a second midpoint between the second pair of antennas with the second angle of arrival being on either side, respectively, of the second line between the second pair of antennas. 
     
     
       6. The method according to  claim 1 , further comprising the step of:
 determining a distance to the portable key device from one of the antennas; and 
 wherein the step of determining the position comprises determining the position based on the distance. 
 
     
     
       7. The method according to  claim 6 , wherein the step of determining the position comprises determining the position in three dimensions. 
     
     
       8. An access control device arranged to determine whether a portable key device is located in an active area in relation to a barrier, wherein the active area is on the outside of the barrier, the access control device comprising:
 a processor; and 
 a memory storing instructions that, when executed by the processor, cause the access control device to: 
 detect a first angle of arrival of the wireless signal from the portable key device using a first pair of separated antennas; 
 detect a second angle of arrival of the wireless signal from the portable key device using a second pair of separated antennas, wherein the first pair of antennas is located on the outside of the barrier and the second pair of antennas is located on inside of the barrier; 
 determine a first pair of directions based on the first angle of arrival; 
 determine a second pair of directions based on the second angle of arrival; 
 determine a position of the portable key device to be where one of the first pair of directions intersects one of the second pair of directions, wherein any intersection located between a first line between the first pair of antennas and a second line between the second pair of antennas is discarded for determining the position; and 
 determining whether the portable key device is located in the active area based on the position. 
 
     
     
       9. The access control device according to  claim 8 , wherein the instructions to detect the first angle of arrival comprise instructions that, when executed by the processor, cause the access control device to detect the first angle of arrival based on a time difference of receiving the wireless signal in the first pair of separated antennas and wherein the instruction to detect the second angle of arrival comprise instructions that, when executed by the processor, cause the access control device to detecting the second angle of arrival based on a time difference of receiving the wireless signal in the second pair of separated antennas. 
     
     
       10. The access control device according to  claim 8 , wherein the instructions to determine the first pair of directions comprise instructions that, when executed by the processor, cause the access control device to determine each direction of the first pair of directions as a direction from a first midpoint between the first pair of antennas with the first angle of arrival being on either side, respectively, of the first line between the first pair of antennas, and the instructions to determine a second pair of directions comprise instructions that, when executed by the processor, cause the access control device to determine each direction of the second pair of directions as a direction from a second midpoint between the second pair of antennas with the second angle of arrival being on either side, respectively, of a second line between the second pair of antennas. 
     
     
       11. The access control device according to  claim 8 , further comprising instructions that, when executed by the processor, cause the access control device to determine a distance to the portable key device from one of the antennas; and wherein the instructions to determine the position comprise instructions that, when executed by the processor, cause the access control device to determine the position based on the distance. 
     
     
       12. A non-transitory computer program for determining whether a portable key device is located in an active area in relation to a barrier, wherein the active area is on outside of the barrier, the computer program comprising computer program code which, when run on an access control device, causes the access control device to:
 detect a first angle of arrival of the wireless signal from the portable key device using a first pair of separated antennas; 
 detect a second angle of arrival of the wireless signal from the portable key device using a second pair of separated antennas, wherein the first pair of antennas is located on the outside of the barrier and the second pair of antennas is located on inside of the barrier; 
 determine a first pair of directions based on the first angle of arrival; 
 determine a second pair of directions based on the second angle of arrival; and 
 determine a position of the portable key device to be where one of the first pair of directions intersects one of the second pair of directions, wherein any intersection located between a first line between the first pair of antennas and a second line between the second pair of antennas is discarded for determining the position; and 
 determine whether the portable key device is located in the active area based on the position. 
 
     
     
       13. A non-transitory computer program product comprising a computer program according to  claim 12  and a computer readable means on which the computer program is stored.